An electronic sensor device for detecting the vibration related to an amplification system within stringed musical instruments. The described stringed instrument has a bridge on its face panel or soundboard, and on the back of the soundboard a bridge reinforcement plate at an equivalent position. The bridge comprises string pin holes and a saddle slot. The strings pass through the string pin holes from outside and are affixed to the bridge reinforcement plate. Strings are normally attached to the string pins.
To efficiently transfer vibrations to the surrounding atmosphere, to create sound, the body of an acoustic guitar is comprised of relatively thin sections of, usually timber or other thin substrates. However such thin substrates will not only sympathetically vibrate with the strings, but also the electronically amplified sound of the instrument, that is, sound arising from speakers in the vicinity of instrument, so forming ongoing vibrations or a loop within the instrument's thin sections and strings and then the amplification system: This ‘loop’ is commonly referred as ‘feedback’.
The saddle is the terminating point of the guitar's strings. The position of the saddle determines the length of the guitar's strings, or the “musical scale length”. Because the saddle is located at the end of the strings, it can effectively pick up the vibration of the strings, as the strings vibrate the resonant cavity of the guitar from that point. In order to avoid “feedback”, the pickup device is usually installed under the saddle and usually placed in the saddle slot between the saddle and the bridge.
There are Three Main Existing Methods for Sound Pickup Technology:
1) Hard strip: six small piezoelectric ceramic elements or pieces: each responsible for picking up vibration of a string. The six ceramic pieces are glued in a metal strip or shell. Layers of adhesive are necessary to manufacture the device, and they compromise efficient coupling, and because the piezoelectric ceramic elements are small, electrical output is low;
2) Soft piezo strips: Soft strips are wrapped in plastic or other pliable materials, or else are comprised of ‘piezoelectric-plastic’. The greater the number of layers the higher the electrical output and therefore sensitivity: However soft plastic material is less effective in sound transmission than solids, and so the efficiency of the transducer is compromised, as both strip type pickups rely on the transverse force of strings in applying downward force to the saddle, so that the saddle couples the pickup device to the guitar with a downward force.
3) Six large piezoelectric ceramic rods equidistant apart, fixed up under the bridge on an aluminum bar base, comprising screws and nuts on both sides. However the third type of pickup system can only be installed if an instrument that has been manufactured specifically for the installation of the said device: special holes or apertures must have been drilled or routed or otherwise created in the instrument's soundboard and bridge during manufacture.
This system cannot therefore be easily installed in existing instruments. The current invention solves this problem: so that installation is able to be performed with relative ease on existing instruments, which have not been specially manufactured so that the piezoelectric elements sensing device describe in 3 are able to be installed.
The Shortcomings of the Existing Technology are as Follows:
1. In existing technologies, both the hard piezoelectric strips and the soft piezoelectric strips can only be coupled or clamped by the downward pressure of the saddle, which is applied after the strings are tuned or tightened. This leads to poor coupling and feedback. Furthermore, because the devices are not well coupled, they are relatively insensitive to the surrounding structure's resonance. Further, the non-sensing side of ‘strip type piezoelectric sensors’, comprise very little mass and therefore are relatively inefficient. The reason for this, is that due to the light weight of such devices, there is insufficient difference between the sensing side and the non-sensing side which, to be efficient, should tend to inertia, so that the created analogue signal is a measure of the difference between one side and the other. Further there is insufficient space within the saddle slot to house piezoelectric elements of substantial and more ideal mass and therefore electrical output.
2. It is known that the sound waves decreases when passing through softer materials or when there is a gap between devices. Sound travels more efficiently through solid materials than it does through soft or elastic materials, or where there are gaps. And so when the soft strip is mounted on an acoustic guitar, the transmission efficiency of the soft strip is not as high as that of harder solid materials. In existing technology, piezoelectric elements are assembled by means of adhesive, usually within a metallic U channel or strip. Relatively soft or elastic adhesive layers compromises the carrying of sound waves.
3. Within the first two existing pickup devices referred to, piezoelectric elements must be installed within the saddle slot under the saddle. The space within the saddle slot under the saddle limits the volume of the piezoelectric material that can be used. And so where the output of the electric signal is proportional to the volume of the piezoelectric material, so the output of the electric signal is also relatively limited. Further in that prior art, the commonly used hard and soft strip type piezoelectric pickups efficiency is dependent upon the flatness of the base of the saddle slot. If the bottom of the saddle slot is uneven, the output of each of the six strings is likely to be dissimilar, compromising the performance of the device: as some strings are less sensed than others.